Cause and Effect & Validity

Question 1

State the criteria for Cause and Effect

Answer 1

Cause has to precede the effect in time.

Cause and effect must be correlated with each other.

The correlation between cause and effect cannot be explained by another variable.

Manipulating the cause, changes the effect.

Question 2

State the two types of Validity

Answer 2

Internal validity: did the IV cause the DV?

External validity: relates to how findings can be generalised to the population

Question 3

State the nine threats to Internal validity

Answer 3

History
Maturation 
Testing
Instrumentation
Statistical regression
Selection bias
Experimental mortality 
Selection-maturation 
Expectancy

Question 4

Define the term History

Answer 4

Events that are not part of the treatment.

For example: when testing VO2 max on sedentary subjects, they train outside of the study which effects results.

Question 5

Define the term Maturation

Answer 5

Events that occur due to the passage of time not due to the manipulation.

Question 6

Define the term Testing

Answer 6

Effects of more than one test administration.

For example: VO2 max

Question 7

Define the term Instrumentation

Answer 7

The change in calibration of a measuring tool which in turn effects results.

Question 8

Define the term Statistical regression

Answer 8

The selection made based on an extreme score prior to the study. During study the previous observation leads to a regression from the norm.

Question 9

Define the term Selection bias

Answer 9

Non-random selection of participants.

Question 10

Define the term Experimental mortality

Answer 10

The differential loss of participants, due to withdrawal from the study.

Question 11

Define the term Selection-maturation interaction

Answer 11

The passage of time, influencing groups differently.

Question 12

Define the term Expectancy

Answer 12

The experimenters expectancy / anticipation of participants.

Question 13

State the four threats to External validity

Answer 13

Reactivity to interactive effects of testing

Interaction of selection biases and treatment

Reactivity effects of experimental arrangements

Multiple treatment inteference

Question 14

Define Reactivity or interactive effects of testing

Answer 14

Pre test which may make participants more sensitive to testing.

For example: VO2 max before experiment

Question 15

Define Interaction of selection biases and treatment

Answer 15

Treatment may work only on participants which were selected based on specific characteristics

Question 16

Define Reactivity effects of experimental arrangements

Answer 16

Setting constraints may influence generalisability.

Question 17

Define Multiple treatment interference

Answer 17

One treatment may influence the next

Question 18

State the five Controls to Internal validity

Answer 18

Randomisation

Blind set-ups

Reactive effects of testing

Instrumentation

Differential mortality

Question 19

Define Randomisation

Answer 19

Participants are selected randomly

Can be matched pairs (not groups)

Randomising treatments or counterbalancing

Question 20

Define Blind-setups

Answer 20

Double blind setup- neither participant nor researcher are aware of experimental procedure

Single-blind: participants unaware of experimental procedure

Placebos

Question 21

Define Reactive effects of testing as a way of controlling Internal validity

Answer 21

The elimination of a pre-test

Question 22

Define Instrumentation as a way of controlling Internal validity

Answer 22

The constant checking and calibration of equipment

Question 23

Define Differential mortality as a way of controlling Internal validity

Answer 23

Keeping hold of participants during experimental procedures

Question 24

Describe the four ways of controlling External validity

Answer 24

Selecting; participants, treatments, situations and tests to represent a larger population.

Consider the removal of the pre-test

Randomisation

Ecological validity - does the setting reflect the real world?

Question 25

Define the term True experiment

Answer 25

Where the manipulation of the IV and the participants have been randomly assigned to the different levels of the IV